Problem: It takes 54 minutes for 10 people to paint 10 walls. How many minutes does it take 16 people to paint 16 walls?
Answer: Imagine that each person is assigned one wall, and all 10 people begin painting at the same time. Since everyone will finish painting their assigned wall after 54 minutes, it takes one person 54 minutes to paint one wall. If we have 16 people and 16 walls, we can again assign one wall to each person. Everyone will take 54 minutes to paint their assigned wall. In other words, it takes 54 minutes for 16 people to paint 16 walls.